I had a few mod ideas to share, I could not find another topic for this...

One thing that I was missing in TH design was the ability to control the mixer. All of this can be done with 5V Logic. The truth table is available on the Data sheet. Has anybody experimented with this? Obviously it would be VERY cool to switch between NOISE and VCO, and if done with a high frequency clock, one could even achieve a quasi mixing effect. At lower frequencies new waveforms could (possibly) be achieved.

The data sheet seems to be a bit cryptic in its description of the different truths... so I am not completely sure what is happening when the mixer is set to "SLF/ Noise" for instance.
SLF iss Texas Inst. speakl for LFO btw.

Another cool feature that I would like to make use of is the other envelope modes available. The envelope is able to be one shot, high (both of which are implemented in the TH design) and also triggered by the VCO (and further by every other VCO cycle, perhaps more useful?). This should be a simple mod to achieve by cutting some traces and using a 4 position rotary rather thaN THE SPST switch to select between "always on" and "envelope" for the output. Triggering the envelope with the VCO would seem to me to be able to produce som very cool effects when used with the NOISE.

I'd thought of the same mixing schemes myself, but buried in projects like most everyone else here on the forum. The Noise/VCO mix is not very good as the noise seems to drown out the VCO. Surprisingly, the Noise/LFO(SLF) mix is much better balanced. The LFO needs to be tuned up into the audio range (which it does nicely at the high range switch setting) or you just get the tick-tick-ticking of the LFO (which can probably be used by someone more imaginative than me) but it provides a nice drone voice. I suppose an electronic bagpipe kinda thing could be done with the VCO/LFO mix.

So are you saying that the quasi mixing is automatic achieved when selecting a combination of signals? I know that the mixer does not actually mix, but ratherr it switches between sources... at least that is how understood it. Mixing seemed possible by muxing at high frequencies as far as I could tell, but from what you are saying the different modes, SLF/NOISE for ex. are already "mixed."

I still think it would be cool to tie a couple of schmitt trigger (running off the 5V suppply) into the circuit to select between Noise and VCO at rates determined by the user (via external LFO).

Well the mixer works like 3 switches switching on or off each of the 3 audio sources (noise, LFO, or VCO). The combination of A, B and C will select one, two or all 3 signals premixed at a fixed level. I'm not how sure how fast the switching is, but as you theorized, if it is fast enough, one should be able to PWM the individual voumes.

yeah, it'd be cool to try...just too busy now. Good luck if you get any interesting results!

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